Intake and exhaust arrangement for a rotary-piston internal combustion engine

ABSTRACT

An internal combustion engine, in which two sets of four pistons rotate about the axis of a cylindrical casing wall and additionally move angularly relative to each other about the casing axis to expand and contract combustion chambers circumferentially extending between the pistons of the two sets having circumferential faces of different width, and each wider circumferential face is formed with two radially open grooves in respective axially spaced planes, the two grooves being open only in respective, opposite, circumferential directions for communication with respective combustion chambers and connecting the combustion chambers from time to time with intake and exhaust ports formed in the casing in the aforementioned axially spaced planes.

United States Patent Sabet 1 Dec. 18, 1973 [54] INTAKE AND EXHAUST ARRANGEMENT 3,106,912 10/1963 Kahlert 123/8.47 FOR A ROTARY PIST()N INTERNAL 3,282,258 11/1966 Sinnott COMBUSTION ENGINE 3,302,625 2/1967 Cunningham 123/8.47 [76] Inventor: Huschang Saba, FOREIGN PATENTS OR APPLICATIONS Ed d Pf iff -St 67 822,397 12/1937 France 123/847 Stuttgart, Germany Primary ExaminerC1arence R. Gordon [22] Flled: 1972 Attorney-Kurt Kelmun et a1. [21] Appl. No.: 284,896

Related US. Application Data [57] ABSTRACT [63] COminuatiOmimpm-t f Ser, 1373370 April 27' An internal combustion engine, in which two sets of 1971,-Put, No. 3,736,080. four pistons rotate about the axis of a cylindrical casing wall and additionally move angularly relative to [30] Foreign Application Priorit Data each other about the casing axis to expand and consept 25 Germany P H 36 462.0 tract combustion chambers circumferentially extending between the pistons of the two sets having circum- 52] us. c1 123/s.47, 418/34, 418/68 feremial faces of different Width, and each Wider i 51 1111. C1. F02b 55/14 cumferemiel face is formed with radially Open 581 Field of Search 123/847; 418/33, grooves in respective axially Spaced Planes, the

418/34, 68 grooves being open only in respective, opposite, circumferential directions for communication with re- [56] References Cited spective combustion chambers and connecting the UNITED STATES PATENTS combustion chambers from time to time with intake and exhaust ports formed in the casing in the afore' 2/1212 2734,48) 2/1956 'lschudi 1 .1 123/847 -9 Claims, 5 Drawing Figures PAIENTH DEC I8 1975 Fig. 4 71,

I l l 4 INTAKE AND EXHAUST ARRANGEMENT FOR A ROTARY-PISTON INTERNAL COMBUSTION ENGINE This application is a continuation-in-part of the copending application Ser. No. 137,870, filed on Apr. 27, 1971, now U.S. Pat. No. 3,376,080.

This invention relates to internal combustion engines having rotary pistons, and particularly to an improved intake and exhaust arrangement in a rotary piston engine of the type disclosed in the afore-mentioned copending application.

The engine of the earlier application has eight pistons constituting two sets of four pistons each which rotate in a casing of circular cross section about the casing axis and also move angularly relative to each other between two terminal positions. Each piston has two radially extending faces, and the faces of the several pistons define combustion chambers between respective pistons of the sets, each combustion chamber expanding to a greatest angular width relative to the casing axis in one of the terminal positions of the two sets, and contracting to its smallest angular width in the other terminal position of the associated respective pistons of the two sets. The circumferential faces of all pistons sealingly engage the engine casing, the circumferential faces of the pistons in one set having a substantially greater angular width relative to the casing axis than the circumferential faces of the pistons in the other set. During normal operation of the engine, the pistons having wider circumferential faces rotate at uniform speed while the circumferential or angular speed or the narrow-faced pistons varies cyclically to produce the desired angular movement, the two sets of pistons being mechanically linked as by gearing.

It has been found that the afore-described engine operates well if the intake of a fuel mixture to the expanding combustion chambers and the exhaust of the spent mixture from the contracting chambers is controlled by valves of the type employed in automotive reciprocating piston engines operating in a four-stroke cycle, and that intake and exhaust ports opened and closed by the moving pistons in a manner conventional in automotive engines operating in a two-stroke cycle may be provided in the engine casing for successful operation at low or moderate rotary speeds. When the engine is operated at very high speeds, precise timing of the open and closed periods of the ports is difficult because of the differences in mass and circumferential width of the two sets of pistons, particularly when one set rotates at uniform speed.

These timing difficulties have now been overcome in an engine having a casing formed with intake and exhaust ports by providing each piston of the set having circumferential faces of greater angular width with two ducts which are open in respective opposite circumferential directions toward respective combustion chambers while being sealed from the respective other combustion chambers. Each duct has an opening directed toward the casing and a portion of the circumferential piston face extends between the opening and the associated other combustion chamber. The two openings are located in respective, axially spaced, radial planes, and the intake andexhaust ports of the casing are re spectively located in these radial planes.

Other features, additional objects, and many of the attendant advantages of this invention will be appreciated readily as the same becomes better understood by reference to the following detailed description of preferred embodiments when considered in connection with the appended drawing in which:

FIG. I shows one set of pistons and an associated end wall of the engine casing in a perspective view;

FIG. 2 illustrates the device of FIG. 1 together with the other set of pistons and a mounting sleeve associated with the other set in fragmentary plan view taken in the direction of the engine axis;

FIG. 3 is a fragmentary, developed, elevational view of the two sets of pistons, the ports in the engine casing being indicated in phantom view;

FIG. 4 shows the apparatus of FIG. 3 in a different operating position and in an analogous view; and

FIG. 5 is a fragmentary, developed, elevational view of a modified casing enveloping pistons identical with those of FIGS. 1 to 4.

The drawing shows only as much of the rotary piston, internal-combustion engine disclosed in the aforementioned copending application as is needed for an understanding of the improvement contributed -by the instant invention. The engine has a generally cylindrical, tubular casing omitted from FIGS. 1 to 4. The cavity in the casing is axially bounded by two annular end walls 2 which rotate freely relative to the casing. A set of four identical pistons l is equiangularly offset about the common axis of the non-illustrated casing and of the end walls 2 hereinafter referred to as the engine axis. Each piston 1 has the approximate cross sectional shape of an isoceles triangle whose equal sides are straight and define radially extending flat faces of the piston which converge toward the engine axis. The third side of the approximate triangle is convexly arcuate and has a radius of curvature substantially identical with that of the inner casing face. The circumferential face of each piston thus is a portion of a straight cylinder.

The illustrated end wall 2 is integral with the four pistons l, and the non-illustrated similar end wall is normally attached to radial faces of the pistons 1 by means of screws threadedly engaging two of four bores 1' in the radial piston face, the other two bores permitting a cooling fluid to be circulated through each hollow piston 1 in a manner more fully described in the aforementioned application.

The circumferential, cylindrically arcuate face of each piston 1 is formed with two grooves 3, 4 in respective, axially spaced, radial planes. In the assembled condition of the engine, the grooves 3, 4 in each piston 1 form ducts which are open in respective opposite, circumferential directions while being sealed in the other circumferential direction and from the other groove by an integral portion of the circumferential piston face. The grooves 3, 4 are open over their entire circumferential length in a radially outward direction, that is, a radial opening of each duct is directed toward the casing. Respective parts of the two grooves 3, 4 and of their radial openings are circumferentially coextensive.

Resilient strips 7 on the circumferential faces of the pistons 1 and corresponding sealing strips 8 on the illustrated end wall 2 engage the casing in the assembled engine, while similar, axially elongated sealing strips 10 project from the radially innermost narrow face of each piston for engagement with a tubular mounting sleeve 9, the sleeve being movably sealed in the central openings of the end wall 2 and of the corresponding nonillustrated end wall. As is shown in FIG. 2, the four pistons 11 of the other set are fixedly fastened on the sleeve 9 in equiangularly spaced relationship, each piston 11 being interposed circumferentially between two pistons l in the assembled engine, as is seen in FIG. 2, and movably sealed to the radial end walls by resilient strips 11, similar strips on the outer circumferential face being obscured in FIG. 2.

Each piston 11 has outer and inner circumferential faces which are cylindrically arcuate about the engine axis and are connected by two radially extending flat faces which converge in a radially outward direction. The two flat faces of each piston 11 and respective flat faces of the two circumferentially adjacent pistons l define two chambers and 6 which expand and contract as each piston 11 is oscillated during engine operation between adjacent pistons 1 by a gear linkage more fully described in the afore-mentioned copending application. In FIG. 2, the fully shown piston 11 is in one terminal position of its angular movement relative to the pistons l in which the chamber 6 has its smallest angular width relative to the engine axis, and the flat piston faces bounding the chamber 6 are parallel. The chamber 5 is at its greatest angular width. In the other terminal position of the pistons 11 relative to the pistons 1, the angular dimensions of the chambers 5, 6 are interchanged.

This condition of the chambers 5,6 is seen in FIG. 3. The engine casing, not itself seen in FIG. 3, has half as many intake ports 14 and exhaust ports 13 as there are pistons in each set, and only one port 13, 14 is shown in FIG. 3. The direction of movement of the piston 1 relative to the casing is from the right to the left, as indicated by an arrow in FIG. 3. The chamber 5 has reached its smallest volume and moved out of communication with the exhaust port 13. As the pistons continue their movement relative to the casing, the piston 11 will clear the port 14 and move away from the piston l to expand the chamber 5 while the latter communicates with the intake port 14 and the source of fuel mixture connected therewith, but not shown since it may be entirely conventional. Communication between the intake port 14 and the expanding chamber 5 is maintained through the duct 3 while the piston 1 travels over the portion of the casing face containing the port 14.

As viewed in FIG. 4, the piston 11 illustrated in FIG. 3 has moved out of the field of view and will thereafter return toward the piston l for compressing the fuel mixture in the chamber 5 for subsequent ignition by means of a non-illustrated spark plug. The chamber 6 shown between the piston 1 and a piston 11 not visible in FIG. 3 is at its largest volume after explosion of the fuel mixture and about to communicate with the exhaust port 13 through the duct 4 while the chamber 6 contracts and the spent fuel mixture is exhausted through the port 13. As shown in FIG. 4, the chamber 6 has reached its minimum volume after conclusion of the exhausting stage and is ready for receiving fuel mixture from the port 14.

The two dimensionally identical ports l3, 14 are rectangular, and their axial height is equal to the corresponding dimension of the ducts 3, 4. Their circumferential width is practically equal to the corresponding dimension of the outer circumferential face of each piston l 1 and to the imperforate portion of the circumferential face of each piston I which separates the ducts 3, 4 from the adjacent combustion chambers 5, 6 with which the duct does not communicate. There cannot be direct flow of fluid between the ports 13, 14. The two ports 13, 14 are spaced from each other circumferentially a distance equal to the smallest width of each combustion chamber as shown at 5 in FIG. 3, for example.

If it is desired to start expulsion of the spent combustion gases before the combustion chamber reached its smallest volume and to continue the fuel mixture intake beyond the position of the pistons 1, 1 1 in which a combustion chamber has its greatest volume, the angular width of the intake port is increased in the direction of piston movement as is shown at 14 in FIG. 5, and the angular width of the exhaust port is increased in a direction opposite to the direction of piston rotation, as shown at 13' in FIG. 5, the exhaust port 13' being partitioned as will presently be discussed.

In the embodiment illustrated in FIG. 5, the engine casing 12 is provided with as many pairs of ports as there are pistons in each set, the engine operates in a two-stroke cycle, and each combustion chamber is scavenged of spent fuel mixture by admitted fresh fuel mixture, a small portionof each intake port 14' being circumferentially coextensive with a corresponding portion of the associated exhaust port 13'.

Because the angular width of the port 14 is greater than that of the circumferential face portion of the piston l which separates the duct 3 from the combustion chamber 6 in FIG. 5, and the angular width of the port 13, taken as a whole, is greater than the corresponding width of the outer circumferential face of the piston 11, a partition 15, which is a portion of the casing 12, divided the port 13' into two exhaust ports 16, 17 each having an angular width relative to the engine axis which is smaller than that of the outer circumferential face of the piston 11 and much greater than the corresponding dimension of the partition 15. The two ports 16, 17 may be connected with separate exhaust systems or with respective conduits in a jet pump arrangement as disclosed and claimed in the simultaneously filed application for an Exhaust arrangement in a rotarypiston, internal-combustion engine, Ser. No. 284,897.

This arrangement prevents combustion products from flowing from a trailing combustion chamber under their higher pressure into a leading chamber in which a lower pressure prevails at the end of the exhaust stage. Such flow would also interfere with effective scavenging flow of fresh fuel mixture between two adjacent chambers.

The grooves 3, 4 are most conveniently formed in the pistons l as by machining or by casting, but ducts open toward one of two adjacent combustion chambers and sealed from the other combustion chamber while having an opening directed toward the inner face of an engine casing of the type described may be formed in other ways, and they need not be open toward the easing over their entire circumferential length to perform in the manner described.

It should be understood, therefore, that the foregoing disclosure relates only to preferred embodiments of the invention, and that it is intended to cover all changes and modifications of the invention herein chosen for the purpose of the disclosure that do not depart from the spirit and scope of the appended claims.

What is claimed is:

1. In a rotary-piston internal-combustion engine having a casing of circular cross section at right angles to an axis of said casing, two sets of pistons mounted in the casing for angular movement relative to each other between two terminal positions and for rotation about said axis, each piston having two radially extending faces, said faces circumferentially defining combustion chambers between respective pistons of said sets, each of the combustion chambers expanding to a greatest angular width relative to said axis in one of said terminal positions and contracting to the smallest angular width thereof in the other terminal position of the associatcd respective pistons of said two sets, respective circumferential faces of said pistons sealingly engaging said casing, the circumferential faces of the pistons in one of said sets having an angular width relative to said axis substantially greater than the angular width of the circumferential faces of the pistons in the other set, the improvement which comprises:

a. each piston in said one set being formed with two duets open in respective opposite circumferential directions toward respective combustion chambers while being sealed from the respective other combustion chambers, each duct having an opening directed toward said casing, a portion of said circumferential face extending between each opening and the associated other combustion chamber, said openings being located in respective axially spaced radial planes; and

b. said casings being formed with a pair of ports respectively located in said radial planes.

2. In an engine as set forth in claim 1, said portions of said circumferential faces in the pistons of said one set having an angular width relative to said axis substantially equal to the angular width of each circumferential face in the pistons of said other set.

3. In an engine as set forth in claim 2, the respective angular widths of said ports being substantially equal to the angular width of the circumferential faces in the pistons of said other set.

4. In an engine as set forth in claim 1, said ports being spaced from each other in a circumferential direction by an angle relative to said axis substantially equal to said smallest angular width of each of said combustion chambers.

5. In an engine as set forth in claim 1, the respective angular widths of said ports being greater than the angular width of the circumferential faces in the pistons of said other set, said ports being angularly offset relative to said axis.

6. In an engine as set forth in claim 1, the angular width of one of said ports relative to said axis being greater than the angular width of the circumferential faces in the pistons of said other set, a small portion of said one port being circumferentially coextensive with a corresponding portion of the other port.

7. In an engine as set forth in claim I, said casing being formed with a third port in one of said radial planes, a portion of said casing circumferentially separating said third port from the member of said pair of ports located in said one radial plane, the respective angular widths of said third port and of said member of the pair of ports relative to said axis being smaller than the corresponding width of each of said circumferential faces of the pistons of said other set, and much greater than the corresponding width of said portion of the easing.

8. In an engine as set forth in claim 1, the two ducts formed in each piston of said one set being circumferentially elongated and having respective circumferentially coextensive portions.

9. In an engine as set forth in claim 1, respective portions of said openings of said two ducts being circumferentially coextensive. 

1. In a rotary-piston internal-combustion engine having a casing of circular cross section at right angles to an axis of said casing, two sets of pistons mounted in the casing for angular movement relative to each other between two terminal positions and for rotation about said axis, each piston having two radially extending faces, said faces circumferentially defining combustion chambers between respective pistons of said sets, each of the combustion chambers expanding to a greatest angular width relative to said axis in one of said terminal positions and contracting to the smallest angular width thereof in the other terminal position of the associated respective pistons of said two sets, respective circumferential faces of said pistons sealingly engaging said casing, the circumFerential faces of the pistons in one of said sets having an angular width relative to said axis substantially greater than the angular width of the circumferential faces of the pistons in the other set, the improvement which comprises: a. each piston in said one set being formed with two ducts open in respective opposite circumferential directions toward respective combustion chambers while being sealed from the respective other combustion chambers, each duct having an opening directed toward said casing, a portion of said circumferential face extending between each opening and the associated other combustion chamber, said openings being located in respective axially spaced radial planes; and b. said casings being formed with a pair of ports respectively located in said radial planes.
 2. In an engine as set forth in claim 1, said portions of said circumferential faces in the pistons of said one set having an angular width relative to said axis substantially equal to the angular width of each circumferential face in the pistons of said other set.
 3. In an engine as set forth in claim 2, the respective angular widths of said ports being substantially equal to the angular width of the circumferential faces in the pistons of said other set.
 4. In an engine as set forth in claim 1, said ports being spaced from each other in a circumferential direction by an angle relative to said axis substantially equal to said smallest angular width of each of said combustion chambers.
 5. In an engine as set forth in claim 1, the respective angular widths of said ports being greater than the angular width of the circumferential faces in the pistons of said other set, said ports being angularly offset relative to said axis.
 6. In an engine as set forth in claim 1, the angular width of one of said ports relative to said axis being greater than the angular width of the circumferential faces in the pistons of said other set, a small portion of said one port being circumferentially coextensive with a corresponding portion of the other port.
 7. In an engine as set forth in claim 1, said casing being formed with a third port in one of said radial planes, a portion of said casing circumferentially separating said third port from the member of said pair of ports located in said one radial plane, the respective angular widths of said third port and of said member of the pair of ports relative to said axis being smaller than the corresponding width of each of said circumferential faces of the pistons of said other set, and much greater than the corresponding width of said portion of the casing.
 8. In an engine as set forth in claim 1, the two ducts formed in each piston of said one set being circumferentially elongated and having respective circumferentially coextensive portions.
 9. In an engine as set forth in claim 1, respective portions of said openings of said two ducts being circumferentially coextensive. 